[TowerTalk] Broken Johnny-ball insulators

[Pete Smith]

Yesterday I discovered that the three ceramic "Johnny-ball" insulators that 
isolate my bottom guy-set from the tower are all broken.  They have been up 
8 years and are the only strain insulators left on the tower.  One has lost 
all the ceramic on the top side except for the little bit that separates 
the two guy wires, while the other two have lost parts of the 
non-load-bearing "ears" on either side of the guy wire channels.  The lower 
sides of all three (toward the guy anchors) are apparently intact

Even the worst doesn't look like an imminent failure, and even if it did, 
the guy wires will take the strain directly, though of course I would lose 
the use of the tower for shunt feed on 160.  But I'm really curious what 
would cause such a failure, and if there's anything to do to prevent a 
recurrence.  I have plenty more of the insulators, and the replacement 
doesn't look hard, but it just bothers me not understanding what 
happened.  The climate here isn't THAT extreme -- last winter was pretty 
snowy, but we had only a few days near zero, and this summer didn't break 
100 -- and there are no known unusual atmospheric contaminants, other than 
farmland manure once or twice a year, so I'm stumped.

73, Pete N4ZR
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